examples for a thread about netcdf-cf geometries and the use of coordinates and bounds on the node_coordinates variables

examples_netcdf_coordinates.md

In the example below, given that :featureType = "timeSeries" ;, data variables should be expected to have "coordinates" e.g. someData:coordinates = "time lat lon" ;.

dimensions:
  instance = 2 ;
  node = 5 ;
  time = 4 ;
variables:
  int time(time) ;
    time:units = "days since 2000-01-01" ;
  double lat(instance) ;
    lat:units = "degrees_north" ;
    lat:standard_name = "latitude" ;
  double lon(instance) ;
    lon:units = "degrees_east" ;
    lon:standard_name = "longitude" ;
  int datum ;
    datum:grid_mapping_name = "latitude_longitude" ;
    datum:longitude_of_prime_meridian = 0.0 ;
    datum:semi_major_axis = 6378137.0 ;
    datum:inverse_flattening = 298.257223563 ;
  int geometry_container ;
    geometry_container:geometry_type = "line" ;
    geometry_container:node_count = "node_count" ;
    geometry_container:node_coordinates = "x y" ;
  int node_count(instance) ;
  double x(node) ;
    x:units = "degrees_east" ;
    x:standard_name = "longitude" ;
    x:axis = "X" ;
  double y(node) ;
    y:units = "degrees_north" ;
    y:standard_name = "latitude" ;
    y:axis = "Y" ;
  double someData(instance, time) ;
    someData:coordinates = "time lat lon" ;
    someData:grid_mapping = "datum" ;
    someData:geometry = "geometry_container" ;
// global attributes:
  :Conventions = "CF-1.8" ;
  :featureType = "timeSeries" ;
data:
  time = 1, 2, 3, 4 ;
  lat = 30, 50 ;
  lon = 10, 60 ;
  someData =
    1, 2, 3, 4,
    1, 2, 3, 4 ;
  node_count = 3, 2 ;
  x = 30, 10, 40, 50, 50 ;
  y = 10, 30, 40, 60, 50 ;

The someData:geometry = "geometry_container" ; stands alone with no asserted association to someData:coordinates = "time lat lon" ;. So this would be valid:

dimensions:
  instance = 2 ;
  node = 5 ;
variables:
  int datum ;
    datum:grid_mapping_name = "latitude_longitude" ;
    datum:longitude_of_prime_meridian = 0.0 ;
    datum:semi_major_axis = 6378137.0 ;
    datum:inverse_flattening = 298.257223563 ;
  int geometry_container ;
    geometry_container:geometry_type = "line" ;
    geometry_container:node_count = "node_count" ;
    geometry_container:node_coordinates = "x y" ;
  int node_count(instance) ;
  double x(node) ;
    x:units = "degrees_east" ;
    x:standard_name = "longitude" ;
    x:axis = "X" ;
  double y(node) ;
    y:units = "degrees_north" ;
    y:standard_name = "latitude" ;
    y:axis = "Y" ;
  double someData(instance, time) ;
    someData:grid_mapping = "datum" ;
    someData:geometry = "geometry_container" ;
// global attributes:
  :Conventions = "CF-1.8" ;
data:
  someData =
    1, 2, 3, 4,
    1, 2, 3, 4 ;
  node_count = 3, 2 ;
  x = 30, 10, 40, 50, 50 ;
  y = 10, 30, 40, 60, 50 ;

As would this:

dimensions:
  instance = 2 ;
  node = 5 ;
  time = 4 ;
variables:
  int time(time) ;
    time:units = "days since 2000-01-01" ;
  double lat(instance) ;
    lat:units = "degrees_north" ;
    lat:standard_name = "latitude" ;
  double lon(instance) ;
    lon:units = "degrees_east" ;
    lon:standard_name = "longitude" ;
  int datum ;
    datum:grid_mapping_name = "latitude_longitude" ;
    datum:longitude_of_prime_meridian = 0.0 ;
    datum:semi_major_axis = 6378137.0 ;
    datum:inverse_flattening = 298.257223563 ;
  double someData(instance, time) ;
    someData:coordinates = "time lat lon" ;
    someData:grid_mapping = "datum" ;
    someData:geometry = "geometry_container" ;
// global attributes:
  :Conventions = "CF-1.8" ;
  :featureType = "timeSeries" ;
data:
  time = 1, 2, 3, 4 ;
  lat = 30, 50 ;
  lon = 10, 60 ;
  someData =
    1, 2, 3, 4,
    1, 2, 3, 4 ;